Question. What it the lowest max acceleration a spacecraft can reasonably have and still be able to get into orbit and out of the gravity well of an earthlike planet? I know the space shuttle goes as 3 G (~30 m/s^2 IIRC), but is that the practical local limit? I'm guessing it would be around 10 m/s^2, based off 9.81 m/s being the velocity things fall at on earth, but it's just a guess.
Can anybody give any suggestions/help please?
Acceleration in spaceships
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Technically, as long as you could sustain it, anything over 1G will get you out of the atmosphere eventually.
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It should be noted that if you accelerate yourself to 11 km/s quickly, you don't have to accelerate any more -- 11 km/s is the escape velocity for the Earth's gravitational field.
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Re: Acceleration in spaceships
First, the bolded part is messed up; 9.81 m/s^2 is the acceleration due to gravity on earth, ignoring other forces (like friction).Junghalli wrote:Question. What it the lowest max acceleration a spacecraft can reasonably have and still be able to get into orbit and out of the gravity well of an earthlike planet? I know the space shuttle goes as 3 G (~30 m/s^2 IIRC), but is that the practical local limit? I'm guessing it would be around 10 m/s^2, based off 9.81 m/s being the velocity things fall at on earth, but it's just a guess.
Can anybody give any suggestions/help please?
If you wanted to escape earth's gravity well, you'd just need to have an upwards velocity greater than zero. Starting from rest, you just need a little acceleration for a short time and you'll get some upward velocity. After that, if you can maintain an acceleration greater than or equal to zero, you'll keep going up and out of the gravity well. Technically you just need enough force from your rockets to balance out your weight and drag and give you some velocity.
However, there are some definite advantages to being able to get higher thrust from your spacecraft. The longer you're still trying to get into orbit, the longer you have to apply force to keep yourself up. That takes fuel. Once you're in orbit, high thrust still has its advantages; for example, moving into a higher orbit using a Hohmann transfer orbit requires less delta-v if you do it with two short, high-thrust boosts rather than longer, less forceful acceleration. High forces are very nice to have available.